Civility and topicality of a discussion isn't a measure of how mind-killed that discussion is. I personally very much doubt that I could have discussed Krugman rationally, had I entered the discussion, though I certainly would have been polite about it.
This has no consequence on whether politics is genuinely a mind-killer. I include this disclaimer because it has just occurred to me that (ironically) perhaps the "politics is a mind-killer" issue might be becoming LW's first really political issue, and prompt all the standard arguments-as-soldiers failures of rationality.
What do you mean by mind-killing? Maybe no forward movement towards better understanding?
I blew through all of MoR in about 48 hours, and in an attempt to learn more about the science and philosophy that Harry espouses, I've been reading the sequences and Eliezer's posts on Less Wrong. Eliezer has written extensively about AI, rationality, quantum physics, singularity research, etc. I have a question: how correct has he been? Has his interpretation of quantum physics predicted any subsequently-observed phenomena? Has his understanding of cognitive science and technology allowed him to successfully anticipate the progress of AI research, or has he made any significant advances himself? Is he on the record predicting anything, either right or wrong?
Why is this important: when I read something written by Paul Krugman, I know that he has a Nobel Prize in economics, and I know that he has the best track record of any top pundit in the US in terms of making accurate predictions. Meanwhile, I know that Thomas Friedman is an idiot. Based on this track record, I believe things written by Krugman much more than I believe things written by Friedman. But if I hadn't read Friedman's writing from 2002-2006, then I wouldn't know how terribly wrong he has been, and I would be too credulous about his claims.
Similarly, reading Mike Darwin's predictions about the future of medicine was very enlightening. He was wrong about nearly everything. So now I know to distrust claims that he makes about the pace or extent of subsequent medical research.
Has Eliezer offered anything falsifiable, or put his reputation on the line in any way? "If X and Y don't happen by Z, then I have vastly overestimated the pace of AI research, or I don't understand quantum physics as well as I think I do," etc etc.